NDR #5.7.1 smtp; 553 5.7.1

‘@poczta.onet.pl’ on 9/15/2005 3:39 PM
You do not have permission to send to this recipient. For assistance, contact your system administrator.
access is denied by the policy analysis functions.>
Could someone tell where to check for this policy? The server is an Exchange Server 2003
Thanks,